Synthetic organic polymers, especially polyolefins, are employed widely to create a variety of products. Included among such varied products are: blown and cascade films, extruded sheets, foams, fibers, products made from foam and fibers, woven and knitted fabrics, non-woven fibrous webs and molded articles. Many polymers used in these products, such as polypropylene, exhibit some hydrophobicity (i.e., water resistance), but exhibit no oleophobicity (i.e., oil resistance).
The use of various fluorochemicals to treat topically a variety of fibers and fibrous substrates, such as textiles, carpet, leather, paper and non-woven webs, to impart to those materials desired properties not indigent to the virgin materials, is known. See, for example, Mason Hayek, Waterproofing and Water/Oil Repellency, 24, Kirk-Othmer Encyclopedia of Chemical Technology, pp. 448-455 (3rd ed. 1979) or Banks, Ed., Organofluorine Chemicals and Their Industrial Applications, Ellis Horwood Ltd., Chichester, England, pp. 226-234 (1979). Such fluorochemical compositions include fluorochemical urethane and urea-based oligomers as disclosed in U.S. Pat. No. 3,398,182 (Guenthner et al.), U.S. Pat. No. 4,001,305 (Dear et al.), U.S. Pat. No. 4,215,205 (Landucci), U.S. Pat. No. 4,606,737 (Stern), U.S. Pat. No. 4,668,406 (Chang), U.S. Pat. No. 4,792,354 (Matsuo et al.) and U.S. Pat. No. 5,410,073 (Kirchner); compositions of cationic and non-cationic fluorochemicals as disclosed in U.S. Pat. No. 4,566,981 (Howells); and compositions containing fluorochemical carboxylic acid and epoxidic cationic resin as disclosed in U.S. Pat. No. 4,426,466 (Schwartz). Also known are fluorochemical esters as disclosed by U.S. Pat. No. 3,923,715 (Dettre), U.S. Pat. No. 4,029,585 (Dettre), U.S. Pat. No. 4,264,484 (Patel); and, more specifically, fluorochemical esters derived from dimerized unsaturated fatty acids as disclosed by U.S. Pat. No. 4,539,006 (Langford) and World Published Application WO 93/10085 (Coppens et al.). These fluorochemicals can be applied to various fibrous substrates by methods known in the art, including spraying, padding, and finish bath immersion, or can be applied directly to the fiber before the fiber is woven by incorporating the fluorochemical into the fiber spin finish.
Blending fluorochemicals with synthetic organic polymers and melt extruding fibers from the molten blend to produce fibers and fibrous substrates exhibiting hydrophilicity and oleophilicity also is known. U.S. Pat. No. 5,025,052 (Crater et al.) describes fibers, films and molded articles prepared by melt extruding a blend or mixture of (a) fiber- or film-forming synthetic organic polymers and (b) fluorochemical oxazolidinones to produce fibers, films and molded articles having low surface energy, repellency to oil and water, and resistance to soils. U.S. Pat.
No. 5,380,778 (Buckanin) describes fibers, films, and shaped articles made by melt extruding a blend of a fluorochemical aminoalcohol and a thermoplastic polymer, such as polypropylene. U.S. Pat. No. 5,451,622 (Boardman et al.) describes shaped articles, such as fibers and films, made by melt extruding mixtures of fluorochemical piperazine compound and thermoplastic synthetic polymer. U.S. Pat. No. 5,411,576 (Jones et al.) describes an oily mist resistant electret filter media comprising melt blown electret microfibers and a melt processable fluorochemical having a melting point of at least about 25.degree. C. and a molecular weight of about 500 to 2500, the fluorochemical preferably being a fluorochemical oxazolidinone, fluorochemical piperazine or a perfluorinated alkane having from 15 to 50 carbon atoms. U.S. Pat. No. 5,300,587 (Mascia et al.) describes oil-repellent polymeric compositions made by blending a perfluoropolyether and optionally a radical starter with a thermoplastic polymer, intimately mixing the resulting composition at high temperature for sufficient time to form macroradicals from the polymer, and cooling the final composition to room temperature. U.S. Pat. No. 5,336,717 (Rolando et al.) discloses fluorochemical graft copolymers derived from reacting monomers having terminal olefinic double bonds with fluorochemical olefins having fluoroaliphatic groups and polymerizable double bonds.
While these various fluorochemical melt additives can in some circumstances impart satisfactory hydrophobicity and/or oleophobicity to thermoplastic resins, they typically suffer poor thermal stability above 300.degree. C., a melt processing temperature often encountered in the industry, and they also can be prohibitively expensive, lending self-evident limitation to their commercial utility.